Publicist Max Clifford talks to reporters as he leaves Southwark Crown Court on April 28,in London. Mr Clifford has been found guilty of eight indecent assaults on women and girls as young as 15 by a jury at Southwark Crown Court.Peter Macdiarmid / Getty Images

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He was serving an 8-year prison sentence at Littlehey Prison in Cambridgeshire when he died, Britain's Ministry of Justice said.

Clifford was once as well known as the people he represented — the go-to guy for celebrities looking to limit the damage from drug problems, legal issues or declining popularity.

Publicist Max Clifford talks to reporters as he leaves Southwark Crown Court on April 28,in London. Mr Clifford has been found guilty of eight indecent assaults on women and girls as young as 15 by a jury at Southwark Crown Court.Peter Macdiarmid / Getty Images

His clients included TV mogul Simon Cowell and former Harrods owner Mohamed al-Fayed, as well as dozens of ordinary people who found themselves in the news vortex and sought to sell their stories to the press — a common practice in Britain.

"The allegations in respect of which I have been charged are completely false — very upsetting, very distressing, but completely false," he told reporters outside his home at the time. "I have never indecently assaulted anyone in my life, and this will become clear during the course of the proceedings."

Clifford was arrested as part of an investigation called Operation Yewtree, a wide-ranging inquiry into allegations of past offenses spurred by the case of Jimmy Savile, a well-known British entertainer accused of abusing hundreds of girls and women. He died in 2011.

The Savile case shocked Britain and embarrassed his employer, the BBC, which was accused of killing an investigation into Savile's alleged crimes.

The resulting upheaval is comparable to the stream of sexual misconduct allegations leveled at American actors, politicians and media personalities following revelations about Hollywood producer Harvey Weinstein.

Before he was arrested, Clifford told The Associated Press that he was receiving calls from many celebrities and entertainers who were worried they would be caught up in the widening Savile investigation.

"They're phoning me and saying, 'Max, I'm worried that I'm going to be implicated,'" Clifford said at the time. "A lot of them can't remember what they did last week, never mind 30 or 40 years ago."

Clifford's daughter Louise told the Mail on Sunday that her father first collapsed on Thursday as he was trying to tidy his prison cell. He collapsed again the following day and was taken to a hospital, where suffered a heart attack.

She told the newspaper he had been in a "bad way" in a critical care unit.